U.S. patent application number 13/098240 was filed with the patent office on 2012-11-01 for method for the producing of a light-emitting semiconductor chip, method for the production of a conversion die and light-emitting semiconductor chip.
This patent application is currently assigned to OSRAM SYLVANIA Inc.. Invention is credited to Darshan Kundaliya, Madis Raukas, Norwin Von Malm.
Application Number | 20120273807 13/098240 |
Document ID | / |
Family ID | 45954641 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120273807 |
Kind Code |
A1 |
Von Malm; Norwin ; et
al. |
November 1, 2012 |
Method for the Producing of a Light-Emitting Semiconductor Chip,
Method for the Production of a Conversion Die and Light-Emitting
Semiconductor Chip
Abstract
A light-emitting semiconductor chip is provided, the
semiconductor chip comprising a semiconductor body having a pixel
region with at least two electrically isolated sub-regions, each
sub-region comprising an active layer, which generates
electromagnetic radiation of a first wavelength range during
operation, a separately manufactured ceramic conversion die over a
radiation emission area of at least one sub-region, said conversion
die being configured to convert radiation of the first wavelength
range into electromagnetic radiation of a second wavelength range,
wherein a width of the conversion die does not exceed 100 .mu.m.
Further, a method for the production of a light-emitting
semiconductor chip and method for the production of a conversion
die are provided.
Inventors: |
Von Malm; Norwin;
(Nittendorf-Thumhausen, DE) ; Raukas; Madis;
(Charlestown, MA) ; Kundaliya; Darshan; (Beverly,
MA) |
Assignee: |
OSRAM SYLVANIA Inc.
Danvers
MA
OSRAM Opto Semiconductors GmbH
Regensburg
|
Family ID: |
45954641 |
Appl. No.: |
13/098240 |
Filed: |
April 29, 2011 |
Current U.S.
Class: |
257/88 ; 257/98;
257/E33.061; 427/526; 427/558; 438/29 |
Current CPC
Class: |
H05B 33/10 20130101;
H01L 27/156 20130101; H01L 2933/0041 20130101 |
Class at
Publication: |
257/88 ; 438/29;
427/526; 427/558; 257/98; 257/E33.061 |
International
Class: |
H01L 33/50 20100101
H01L033/50; B05D 3/06 20060101 B05D003/06; C23C 14/04 20060101
C23C014/04 |
Claims
1. Light-emitting semiconductor chip comprising: a semiconductor
body having a pixel region with at least two electrically isolated
sub-regions, each sub-region comprising an active layer, which
generates electromagnetic radiation of a first wavelength range
during operation, and a separately manufactured ceramic conversion
die over a radiation emission area of at least one sub-region, said
conversion die being configured to convert radiation of the first
wavelength range into electromagnetic radiation of a second
wavelength range, wherein a width of the conversion die does not
exceed 100 .mu.m.
2. The light-emitting semiconductor chip of claim 1, wherein the
pixel region comprises a first sub-region and a second sub-region,
each sub-region emitting light of the blue spectral range from its
light emission area, a first conversion die arranged over the light
emission area of the first sub-region, said first conversion die
converts the electromagnetic radiation of the first wavelength
range in electromagnetic radiation of the yellow spectral
range.
3. The light-emitting semiconductor chip of claim 1, wherein the
pixel region comprises a first sub-region, a second sub-region and
a third sub-region, each sub-region emitting light of the blue
spectral range from its light emission area, a first conversion die
arranged over the light emission area of the first sub-region, said
first conversion die converts the electromagnetic radiation of the
first wavelength range into electromagnetic radiation of the red
spectral range, and a second conversion die arranged over the light
emission area of the second sub-region, said second conversion die
converts the electromagnetic radiation of the first wavelength
range into electromagnetic radiation of the green spectral
range.
4. The light-emitting semiconductor chip of claim 1, wherein said
width of the conversion die does not exceed 50 .mu.m.
5. A method for the production of a conversion die, which is
configured to convert electromagnetic radiation of a first
wavelength range into electromagnetic radiation of a second
wavelength, said method comprising the steps of: providing a
substrate; applying a structured photoresist layer on the
substrate; depositing a conversion layer of a conversion material
over the photoresist layer by one of the following methods:
Pulsed-Laser-Deposition, sputtering, e-beam deposition, ion beam
assisted pulsed laser deposition, aerosol deposition; and removing
the photoresist layer, such that discrete conversion dies are
formed on the substrate.
6. The method of claim 5, wherein the conversion dies are
recrystallized by one of the following methods: microwave
annealing, laser annealing, RTA-annealing, annealing in a tube
furnace.
7. The method of claim 5, wherein the substrate comprises a
sacrificial layer and the substrate and the conversion dies are
separated from each other by removing the sacrificial layer.
8. The method of claim 7, wherein the sacrificial layer comprises a
nitride based material.
9. The method of claim 5, wherein the substrate comprises sapphire,
quartz glass, garnets or other oxides.
10. The method of claim 5, wherein the photoresist layer is at
least as thick as the conversion layer.
11. The method of claims 5, wherein a width of the conversion die
does not exceed 100 .mu.m.
12. A method for the production of a light-emitting semiconductor
chip comprising the steps of: providing a substrate; applying a
structured photoresist layer on the substrate, depositing a
conversion layer of a conversion material over the photoresist
layer by one of the following methods: Pulsed-Laser-Deposition,
sputtering, e-beam deposition, ion beam assisted pulsed laser
deposition, aerosol deposition; removing the photoresist layer,
such that a plurality of discrete conversion dies are formed on the
substrate; providing a wafer with a plurality of pixel regions,
each pixel region having at least two electrically isolated
sub-regions, each sub-region comprising an active layer, which is
configured to generate electromagnetic radiation of a first
wavelength range during operation; connecting at least one light
emission area of one sub-region of each pixel region with one
conversion die, and removing the substrate.
13. The method of claim 12, wherein the substrate comprises a
sacrificial layer and the substrate is removed by removing the
sacrificial layer.
14. The method of claim 13, wherein the sacrificial layer comprises
a nitride based material.
15. The method of claim 12, wherein the conversion dies and the
light emission areas of the sub-regions are connected by direct
bonding or by the help of an adhesive layer.
16. The light-emitting semiconductor chip of claim 1, wherein said
width of the conversion die lies between 0.5 .mu.m and 20
.mu.m.
17. The light-emitting semiconductor chip of claim 1, wherein said
width of the conversion die lies between 2 .mu.m and 5 .mu.m.
18. The method of claims 5, wherein a width of the conversion die
does not exceed 50 .mu.m.
19. The method of claims 5, wherein a width of the conversion die
lies between 2 .mu.m and 20 .mu.m.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] Light-emitting semiconductor chips are, for example,
described in the following references: DE 10 2009 037 186, US
2010/0020531 A1, US 2007/0159067 A1, US 2010/0119839 A1, U.S. Pat.
No. 6,696,703 B2 and U.S. Pat. No. 7,285,791 B2.
SUMMARY OF THE INVENTION
[0002] One objective of the present invention is to provide a
light-emitting semiconductor chip for the use in a display, wherein
the efficiency of the display is improved.
[0003] A further objective of the invention is to provide a method
for the production of a conversion die having particularly small
dimensions.
[0004] Furthermore, a simplified method for the production of a
light-emitting semiconductor chip with a conversion die having
particularly small dimensions should be provided.
[0005] A light-emitting semiconductor chip comprises in particular:
[0006] a semiconductor body having a pixel region with at least two
electrically isolated sub-regions, each sub-region comprising an
active layer, which is configured to generate electromagnetic
radiation of a first wavelength range during operation, and [0007]
a separately manufactured ceramic conversion die over a radiation
emission area of at least one sub-region, said conversion die being
configured to convert radiation of the first wavelength range in
electromagnetic radiation of a second wavelength range, wherein a
width of the conversion die does not exceed 100 .mu.m.
[0008] The semiconductor chip is particularly configured for the
use in a display. Further, the semiconductor chip can be used as a
light source for a projection unit.
[0009] The conversion die has the objective to convert radiation of
the active region into light of a different color. In such a way a
semiconductor chip with pixel regions emitting white light can be
achieved.
[0010] In particular, the conversion die has a width which does not
exceed 100 .mu.m. The width of the conversion die preferably does
not exceed a width of the sub-region. Preferably, the width of the
conversion die is equal to the width of the sub-region. It is
particularly preferable that an area of a main face of the
conversion die is equal to the light emission area of the
sub-region. A semiconductor chip with small sub-regions of a
pixel-region allows the construction of a display having improved
efficiency.
[0011] According to an embodiment of the light-emitting
semiconductor chip, the conversion die is arranged in direct
contact with the radiation emission area of the sub-region. It is
particularly preferable that the conversion die is arranged such
that it does not protrude over the light emission area of the
sub-region.
[0012] According to a further embodiment of the semiconductor chip,
the pixel region comprises a first sub-region and a second
sub-region, wherein each sub-region emits light of the blue
spectral range from its light emission area. Further, a first
conversion die is arranged over the light emission area of the
first sub-region, said first conversion die converts the
electromagnetic radiation of the first wavelength range in
electromagnetic radiation of the yellow spectral range. According
to this embodiment, the light emission area of the second
sub-region is preferably free of a conversion die.
[0013] Preferably, the semiconductor chip therefore comprises
sub-regions emitting blue light and sub-regions emitting yellow
light, wherein the yellow light is generated by the conversion of
blue light from the active region into yellow light by the
conversion die, which is arranged over the sub-region. The
light-emitting semiconductor chip preferably emits light with a
white color.
[0014] Since the sub-regions are electrically isolated from each
other, the color of the light emitted by the light-emitting
semiconductor chip can be varied by adapting the current driving
the different sub-regions according to this embodiment.
[0015] According to a further embodiment of the light-emitting
semiconductor chip, the pixel region comprises a first sub-region,
a second sub-region and a third sub-region, each sub-region
emitting light of the blue spectral range from its light emission
area. A first conversion die is arranged over the light emission
area of the first sub-region. Said first conversion die converts
the electromagnetic radiation of the first, blue wavelength range
into electromagnetic radiation of the red spectral range. A second
conversion die is arranged over the light emission area of the
second sub-region, which converts the electromagnetic radiation of
the first, blue wavelength range into electromagnetic radiation of
the green spectral range. According to this embodiment, the third
sub-region is preferably free of a conversion die.
[0016] Preferably, the conversion die is configured for
full-conversion. That means that the part of the radiation
converted by the conversion die is maximized.
[0017] The thickness of the conversion die is one parameter that
determines the amount of the converted radiation. According to one
embodiment the thickness of the conversion die is therefore mapped
to the desired color locus.
[0018] It is particularly preferable that the width of the
conversion die does not exceed 50 .mu.m. The width of the
conversion die lies preferably between 0.5 .mu.m and 20 .mu.m and
particularly preferably between 2 .mu.m and 5 .mu.m.
[0019] A conversion die, which is configured to convert
electromagnetic radiation of the first wavelength range into
electromagnetic radiation of a second wavelength range, can be
produced, for example, by the following method: [0020] providing a
substrate, [0021] applying a structured photoresist layer on the
substrate, [0022] depositing a conversion layer of a conversion
material over the photoresist layer by one of the following
methods: Pulsed-Laser-Deposition, sputtering, e-beam deposition,
ion beam assisted pulsed laser deposition, aerosol deposition and
[0023] removing the photoresist layer, such that discrete
conversion dies are formed on the substrate.
[0024] Preferably, the substrate is only heated minimally during
the application of the conversion material, since otherwise the
photoresist layer might be damaged.
[0025] Preferably, the conversion die comprises a ceramic phosphor
material or is formed by a ceramic conversion material. For example
a garnet doped with rare earths can be used as material for the
conversion die. Further, the conversion die can comprise one of the
following materials or can be formed by one of the following
materials: Cerium-doped garnets, such as
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+,
Tb.sub.3Al.sub.5O.sub.12:Ce.sup.3+; nitrides, such as
M.sub.2Si.sub.5N.sub.8:Eu.sup.2+, wherein M.dbd.Ca,Sr,Ba;
oxynitrides, such as MSi.sub.2O.sub.2N.sub.2:Eu.sup.2+, wherein
M.dbd.Ca, Sr, Ba; Silicates, such as
BaMgSi.sub.4O.sub.10:Eu.sup.2+, M.sub.2SiO.sub.4:Eu.sup.2+, wherein
M.dbd.Ca,Ba,Sr. The conversion die can also comprise one of the
following materials or can be formed by one of the following
materials: MAISiN.sub.3:Eu, MS:Eu, wherein M is a metal selected
from Ca, Sr, Ba; A.sub.2O.sub.3:Eu,Bi, wherein A is selected from
Sc, Y, La, Gd, Lu; other tertiary and higher metal oxides doped
with divalent or trivalent Europium, including functional groups
like molybdates, niobates or tungstates.
[0026] The thickness of the conversion dies lies preferably between
10 .mu.m and 15 .mu.m, including the limits.
[0027] With the help of the structured photoresist layer it is
possible to achieve ceramic conversion dies having small
dimensions.
[0028] According to one embodiment the conversion dies are
recrystallized by one of the following methods: microwave
annealing, laser annealing, Rapid-Thermal-Annealing
(RTA-Annealing), annealing in a tube furnace.
[0029] In general, radiative annealing methods--for example by the
help of microwave radiation or laser light--conductive annealing
methods, wherein the material is in contact with another hot
surface or convective annealing methods, for example heating
through gas or liquid phase contact, can be used. Preferably, the
annealing method rises the temperature of the conversion die
rapidly and not necessarily in a full extend of the object. For
example, the substrate is much cooler than the conversion die
during the annealing process.
[0030] According to a further embodiment, the substrate comprises a
sacrificial layer and the substrate and the conversion dies are
separated from each other by removing the sacrificial layer.
[0031] According to a further embodiment, the sacrificial layer
comprises a nitride based material. For example, the sacrificial
layer comprises one of the following materials or is formed of one
of the following materials: silicon nitride, gallium nitride,
aluminum nitride, titanium nitride, aluminum gallium nitride,
strontium nitride, boron nitride, wolfram nitride, tantalum
nitride, zirconium nitride, hafnium nitride. Furthermore, the
sacrificial layer can comprise zinc oxide or can be formed of zinc
oxide. Such a sacrificial layer and in particular a nitride based
sacrificial layer can, for example, be removed by the help of
UV-radiation or by chemical etching.
[0032] According to on embodiment, the sacrificial layer has a
thickness between 10 nm and 1000 nm, including the limits.
Preferably, the sacrificial layer has a thickness between 50 nm and
1000 nm, including the limits. Particular preferably, the
sacrificial layer has a thickness between 250 nm and 500 nm,
including the limits.
[0033] The substrate, for example, comprises one of the following
materials or is formed by one of the following materials: sapphire,
quartz glass, garnets or other oxides.
[0034] According to a preferred embodiment of the method the
photoresist layer is at least as thick as the conversion layer.
Preferably, the photoresist layer is as twice as thick as the
conversion layer. Such a thick photoresist layer enables removing
the photoresist layer in a manner that discrete conversion dies are
formed on the substrate.
[0035] The thickness of the photoresist layer lies preferably
between 20 .mu.m and 30 .mu.m, including the limits.
[0036] A method for the production of a light-emitting
semiconductor chip comprises in particular the following steps:
[0037] providing a substrate, [0038] applying a structured
photoresist layer on the substrate, [0039] depositing a conversion
layer of a conversion material over the photoresist layer by one of
the following methods: Pulsed-Laser-Deposition, sputtering, e-beam
deposition, ion beam assisted pulsed laser deposition, aerosol
deposition, [0040] removing the photoresist layer, such that a
plurality of discrete conversion dies is formed on substrate,
[0041] providing a wafer with a plurality of pixel regions, each
pixel region having at least two electrically isolated sub-regions,
each sub-region comprising an active layer, which generates
electromagnetic radiation of a first wavelength range during
operation, [0042] connecting at least one sub-region of each pixel
region with one conversion die, and [0043] removing the
substrate.
[0044] With the help of this method it is possible to produce
light-emitting semiconductor chips with conversion dies on wafer
level in an easy way. In particular, this method provides the
conversion dies on the substrate, which simplifies their
arrangement adjusted to the sub-regions. This simplifies the
production of the semiconductor chips in particular if conversion
dies having small dimensions are used.
[0045] The substrate can, for example, be removed with the help of
a sacrificial layer as already described above.
[0046] According to a further embodiment the conversion dies and
the sub-regions are connected to each other by direct bonding or by
the help of an adhesive layer. The adhesive layer can comprise or
can be formed of one of the following materials: silicone, low
melting point glass, hybrid materials of organic adhesives and
inorganic glass.
[0047] For direct bonding, the surface of the conversion die, which
is intended to be connected to the light emission area of the
sub-region as well as the sub-region itself, is preferably coated
with a layer formed by silicon oxide.
[0048] It goes without saying that features which are described in
connection with the method for the production of the conversion die
or the semiconductor chip can be adapted to the method for
production of the semiconductor chip and vice versa.
[0049] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] Further preferred embodiments and developments of the
invention are described in the following in connection with the
Figures.
[0051] FIGS. 1A to 1D schematically show different method steps for
the production of a conversion die according to one embodiment.
[0052] FIGS. 2A to 2F schematically show sectional views of a
semiconductor chip at different method steps according to one
embodiment.
[0053] FIG. 3 shows a schematic sectional view of a semiconductor
chip according to a further embodiment.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0054] Equal or similar elements as well as elements of equal
function are designated with the same reference signs in the
figures. The figures and the proportions of the elements shown in
the figures are not regarded as being shown to scale. Rather,
single elements, in particular layers, can be shown exaggerated in
magnitude for the sake of better presentation.
[0055] According to the embodiment of FIGS. 1A to 1D a substrate 1
is provided for the production of a plurality of conversion dies 2.
The substrate 1 can, for example, be formed of sapphire. On one
main face of the substrate 1 a sacrificial layer 3 is arranged. The
sacrificial layer 3 can, for example, comprise one of the following
materials: silicon nitride, galliumnitride, aluminum nitride,
titanium nitride, aluminum gallium nitride, strontium nitride,
boron nitride, wolfram nitride, tantalum nitride, zirconium
nitride, hafnium nitride, zinc oxide (FIG. 1A).
[0056] A structured photoresist layer 4 is applied on the
sacrificial layer (FIG. 1B). The regions of the substrate which are
free of the photoresist layer 4 are intended to form the later
conversion die 2. The width of the regions on the substrate 1,
which are free of photoresist, preferably does not exceed 100 .mu.m
and particularly preferably does not extend over 50 .mu.m. For
example the width of the regions which are free of photoresist lies
between 0.5 .mu.m and 20 .mu.m and preferably between 2 .mu.m and 5
.mu.m.
[0057] In the present embodiment, the photoresist layer 4 is at
least as thick as the later conversion die 2.
[0058] In a next step, a conversion layer 5 of a conversion
material is deposited over the photoresist layer 4 (FIG. 1C). The
deposition of the conversion material is preferably achieved by one
of the following methods: Pulsed-Laser-Deposition, sputtering,
e-beam deposition, ion beam assisted pulsed laser deposition,
aerosol deposition. The photoresist layer 4 is preferably at least
as thick as the conversion layer 5.
[0059] In a further step the photoresist layer 4 is removed such
that discrete conversion dies 2 are formed on the substrate 1 (FIG.
1D). According to the present embodiment, the conversion dies 2 are
formed of a ceramic material.
[0060] It is particularly preferable that the conversion dies 2 are
tempered in a next step in order to achieve a recrystallization of
the conversion material. A recrystallization can be achieved, for
example by one of the following methods: microwave annealing, laser
annealing, RTA-annealing.
[0061] The material for the conversion die 2 can be chosen from one
of the following materials: Cerium-doped garnets, such as
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+,
Tb.sub.3Al.sub.5O.sub.12:Ce.sup.3+; nitrides, such as
M.sub.2Si.sub.5N.sub.8:Eu.sup.2+, wherein M.dbd.Ca, Sr, Ba;
Oxynitrides, such as MSi.sub.2O.sub.2N.sub.2:Eu.sup.2+, wherein
M.dbd.Ca, Sr, Ba; Silicates, such as
BaMgSi.sub.4O.sub.10:Eu.sup.2+, M.sub.2SiO.sub.4:Eu.sup.2+, wherein
M.dbd.Ca, Ba, Sr. The conversion die can also comprise one of the
following materials or can be formed by one of the following
materials: MAISiN3:Eu, MS:Eu, wherein M is a metal selected from
Ca, Sr, Ba; A203:Eu, Bi, wherein A is selected from Sc, Y, La, Gd,
Lu; other tertiary and higher metal oxides doped with divalent or
trivalent Europium, including functional groups like molybdates,
niobates or tungstates.
[0062] Pulsed-Laser-Deposition of a YAG-phosphor is, for example,
described in one of the following references: Jae Young Choe,
"Luminescence and compositional analysis of
Y.sub.3Al.sub.5O.sub.12:Ce films fabricated by pulsed-laser
deposition", Mat. Res. Innovat. (2002) 6:238-241, T. C. May-Smith,
"Comparative growth study of garnet crystal films fabricated by
pulsed laser deposition", Journal of Crystal Growth 308 (2007)
382-391, M. Kottaisamy et al. "Color tuning of
Y.sub.3Al.sub.5O.sub.12:Ce phosphor and their blend for white
LEDs", Materials Research Bulletin 34 (2008) 1657-1663. The content
of these references is incorporated herein by reference in its
entirety.
[0063] YAG:Ce for example can convert light of the blue spectral
range into light of the yellow spectral range. Phosphors, which can
convert light of the blue spectral range into light of the red
spectral range are for example: M.sub.2Si.sub.5N.sub.8:Eu,
MAISiN.sub.3:Eu, MS:Eu, wherein M is a metal selected from Ca, Sr,
Ba; A.sub.2O.sub.3:Eu, Bi, wherein A is selected from Sc, Y, La,
Gd, Lu.
[0064] Materials for converting light of the blue spectral range
into light of the green spectral range are for example: Lu-garnets,
oxynitrides, M.sub.2SiO.sub.4:Eu and other silicates.
[0065] In the following an embodiment of a method for the
production of a semiconductor chip is described in connection with
FIGS. 2A to 2F.
[0066] A structured semiconductor body 6 is provided (FIG. 2A). The
semiconductor body 6 comprises a plurality of pixel regions 7, each
pixel region 7 having three electrically isolated sub-regions 8.
Each sub-region 8 comprises an active layer 9, which generates
light of the blue spectral range during operation. The active layer
9 preferably comprises a pn-transition, a double hetero structure,
a single quantum structure or a multi quantum structure for the
generation of radiation. Here, the term "quantum structure" means
quantum wells, quantum wires as wells as quantum dots.
[0067] The blue light generated in the active layer 9 is emitted
from a light emission area 10 of the sub-region 8. Semiconductor
bodies with electrically isolated sub-regions are, for example,
described in reference DE 10 2008 011 848 A1, whose content is
incorporated herein by reference in its entirety.
[0068] In a next step the light emission areas 10 of each first
sub-region 8 are covered with an adhesive layer 11 (FIG. 2B). The
adhesive layer 11 can comprise or can be formed of one of the
following materials: silicone, low melting point glass, hybrid
materials of organic adhesives and inorganic glass.
[0069] Then, a substrate 1 with a plurality of conversion dies 2 is
arranged over the light emission areas 10 with the adhesive layers
11. The plurality of conversion dies 2 can, for example, be
produced as described above in connection with FIGS. 1A to 1D.
[0070] The conversion dies 2 are adjusted to the first sub-regions
8 and connected to their light emission areas 10 (FIG. 2C). The
substrate 1 is removed by removing the sacrificial layer 3 between
substrate 1 and conversion dies 2 (FIG. 2D). The sacrificial layer
3 can, for example, comprise a nitride based material, which can be
removed by radiation with ultraviolet light.
[0071] The conversion die 2, which is arranged on the light
emission area 10 of each first sub-region 8 converts the light of
the blue spectral range generated by the active layer 9 into light
of the red spectral range. Preferably, the conversion die 2 is
configured to convert a major part of the blue light emitted from
the light emission area 10 of the sub-region 8 into red light.
[0072] In a next step a plurality of conversion dies 2 is provided
on a substrate 1 again (FIG. 2E). The conversion dies 2 are
configured to convert the light of the blue spectral range
generated by the active layer 9 into light of the green spectral
range.
[0073] The conversion dies 2 are arranged, adjusted and connected
to the light emission areas 10 of the second sub-regions 8 in the
same way as already described in connection with FIGS. 2B to
2D.
[0074] FIG. 2F shows a schematic sectional view of the finished
semiconductor chip. The semiconductor chip comprises a
semiconductor body 6 with a plurality of pixel regions 7. Each
pixel region 7 comprises three sub-regions 8. The sub-regions 8 are
electrically isolated from each other. Each sub-region 8 comprises
an active layer 9 configured to generate blue light, which is
emitted from a light emission area 10 of the sub-region 8.
[0075] The light emission area 10 of each first sub-region 8 is
covered with a conversion die 2, which is configured to convert the
major part of the blue light of the active layer 9 into red
light.
[0076] The light emission area 10 of each second sub-region 8 is
covered with a conversion die 2, which is configured to convert a
major part of the blue light generated by the active layer 9 into
light of the green spectral range.
[0077] Each third sub-region 8 of the pixel regions 7 is free of a
conversion die 2, such that the light emission area 10 of each
third sub-region 8 emits light of the blue spectral range during
operation.
[0078] In the present embodiment each pixel region 7 represents a
VGA-pixel for the use in a display having full color
resolution.
[0079] In contrast to the semiconductor chip according to FIG. 2F,
the semiconductor chip according to the embodiment of FIG. 3 has a
semiconductor body 6 with pixel regions 7 having two electrically
isolated sub-regions 8 instead of three sub-regions 8. Each
sub-region 8 has an active layer 9 configured to generate blue
light, which is emitted from the light emission area 10 of each
sub-region 8.
[0080] Each first sub-region 8 is provided with a conversion die 2,
which converts the blue light of the active layer 9 into yellow
light. Each second sub-region 8 of each pixel region 7 is free of a
conversion die 2, such that the sub-region 8 emits blue light
during operation. The semiconductor chip according to FIG. 3
generates white light during operation.
[0081] The invention is not limited to the description of the
embodiments. Rather, the invention comprises each new feature as
well as each combination of features, particularly each combination
of features of the claims, even if the feature or the combination
of features itself is not explicitly given in the claims or
embodiments.
[0082] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements and/or method steps which perform
substantially the same function in substantially the same way to
achieve the same results are within the scope of the invention.
Moreover, it should be recognized that structures and/or elements
and/or method steps shown and/or described in connection with any
disclosed form or embodiment of the invention may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *